Probes, systems, and methods for examining tissue according to the dielectric properties thereof

ABSTRACT

The present invention relates to probes, systems, and methods for tissue characterization by its dielectric properties, wherein a physical feature of the probe is designed to define and delimit a tissue volume, at a tissue edge, where characterization takes place. Thus, the probe for tissue-edge characterization comprises: a first inner conductor, which comprises: proximal and distal ends, with respect to a tissue edge, along an x-axis; a first sharp edge, inherently associated with the proximal end; at least one feature, issuing from the first inner conductor, substantially at the proximal end, for forming at least one additional sharp edge, operative to enhance localized electrical fringe fields in the tissue, within a generally predefined tissue volume, at the tissue edge, the tissue volume being generally defined by physical parameters associated with the at least one feature; and a dielectric material, which encloses the conductor, in the y-z planes.

CROSS REFERENCE TO RELATED APPLICATION

This Application is a continuation-in-part of pending U.S. patentapplication Ser. No. 10/965,752, filed on Oct. 18, 2004, which is acontinuation of U.S. patent application Ser. No. 10/035,428, filed onJan. 4, 2002, now U.S. Pat. No. 6,813,515, issued on Nov. 2, 2004.

Additionally, this Application is a continuation-in-part of PCT PatentApplication No. PCT/IL2006/000392, filed on Mar. 29, 2006, which claimsthe benefit of U.S. Provisional Patent Application No. 60/665,842, filedon Mar. 29, 2005, now expired.

Additionally, this Application is a continuation-in-part of pending U.S.patent application Ser. No. 10/567,581, filed on Feb. 8, 2006, which isa National Phase of PCT Patent Application No. PCT/IL2006/000015, filedon Jan. 4, 2006, which claims the benefit of U.S. Provisional PatentApplication No. 60/665,842, filed on Mar. 29, 2005, now expired, andU.S. Provisional Patent Application No. 60/641,081, filed on Jan. 4,2005, now expired.

Additionally, this Application is a continuation-in-part of pending U.S.patent application Ser. No. 10/558,831, filed on Nov. 29, 2005, which isa National Phase of PCT Patent Application No. PCT/IL2005/000330, filedon Mar. 23, 2005, which claims the benefit of U.S. Provisional PatentApplication No. 60/555,901, filed on Mar. 23, 2004, now expired.

Additionally, this Application is a continuation-in-part of PCT PatentApplication No. PCT/IL2006/000908, filed on Aug. 6, 2006, which is acontinuation-in-part of pending U.S. patent application Ser. No.11/350,102, filed on Feb. 9, 2006, and a continuation-in-part of pendingU.S. patent application Ser. No. 11/196,732, filed on Aug. 4, 2005.

The disclosures of all of these are incorporated herein by reference.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to probes, systems, and methods forexamining and characterizing tissue by its dielectric properties. Theinvention is particularly useful in differentiating cancerous tissuefrom normal, healthy tissue.

Breast cancer is the second leading cause of cancer deaths in womentoday (after lung cancer) and is the second most common form of canceramong women (after skin cancer). According to the World HealthOrganization, more than 1.2 million people will be diagnosed with breastcancer this year worldwide. The American Cancer Society estimates thatin 2001, approximately 192,200 new cases of invasive breast cancer(Stages I-IV) will be diagnosed among women in the United States; andanother 46,400 women will be diagnosed with ductal carcinoma in situ(DCIS), a non-invasive breast cancer. Though much less common, breastcancer also occurs in men, it being estimated that 1,500 cases will bediagnosed in men in 2001. It is further estimated that 40,600 deathswill occur in 2001 from breast cancer (40,200 among women, 400 amongmen) in the United States. The incidence rate of breast cancer (numberof new breast cancers per 100,000 women) increased by approximately 4%during the 1980s but leveled off, to 100.6 cases per 100,000 women, inthe 1990s. The death rates from breast cancer also declinedsignificantly between 1992 and 1996, with the largest decreases beingamong younger women. Medical experts attribute the decline in breastcancer deaths to earlier detection and more effective treatments.

Mammography is currently the best available screening modality for earlydetection of breast cancer. If the mammography finds a subspecieslegion, the individual is directed to undergo a biopsy or other advancedscreening methods, like ultrasound or MRI CT etc. Only 20% of the womenthat undergo a biopsy proceed to a surgical treatment. The traditionalmethod for histological confirmation involves open surgery biopsy. Analternative is image guided biopsy, which is less invasive and morecostly. The total number of breast biopsies in the U.S. is about 1.2 Mper year. The open biopsy itself is a surgical procedure in which thebreast is open and the tumor or lump is taken out, preferably fully.

The traditional method of biopsy, however, is not always successful andfails to successfully remove the appropriate lesion in about 0.5-17% ofthe cases. Some of the reasons given for unsuccessful biopsiesinclude: 1) poor radiological placement of the localization wire; 2)preoperative and intraoperative dislodgment of the wire; 3) surgicalinaccuracy and inadequacy in excising the appropriate tissue; 4) failureto obtain a specimen radiograph; and 5) failure by the pathologist tolocate the focus of the disease when searching through a larger tissuesample provided by the surgeon.

All of the above reasons stem from a fundamental problem that during thesurgery, the surgeon does not have a real time indication or delineationof the tumor. Because of the difficulty in precisely delineating thecancerous tissue, the surgeon may cut out more than was really necessaryto better assure that the entire tumor was removed.

Today, women with stage I and stage II breast cancer are candidates fortreatment with modified radical mastectomy and with immediatereconstruction. Breast-conserving therapy (BCT) is also available.Breast conservation therapy consists of surgical removal of a breastnodule and of the auxiliary fat pad containing the auxiliary lymph nodes(about a quarter of the breast). This is followed by radiation therapyto the breast and auxiliary areas in some cases. In this type ofoperation, precise margin assessment or delineation of the canceroustissue during the operation is crucial to the success of the proceduresince the goal is to remove the tumor completely while minimizing damageto the breast.

This trade-off between complete removal of the tumor, and conservationof the breast, is usually difficult to optimize because the surgeongenerally does not know the actual margins of the tumor. If the surgeonwere able to clearly delineate the tumor margins during the operation byan on-line margin detector, this trade-off could be better optimized.

The ability of recognizing cancer cells, and especially breast cancercells, using bioimpedance is well established in the biomedicalliterature^(5,6,7,8). The usual method for measuring bioimpedance is byintroducing a sample into a special chamber and applying an AC currentthrough it while recording the voltage across the sample at eachfrequency^(9,10). More modern methods rely on multiple electrodematrices which are connected with the human body and measurephysiological and pathological changes. Some of the methods aim tolocalize tumor cells inside the human body and to form an image^(11,12).Although this method is approved by the FDA, it lacks the necessaryaccuracy for a screening device mainly because of the inherentlimitations of long wavelengths and noise from the contact electrodes.

Another technique, based on magnetic¹³ bioimpedance, measures thebioimpedance by magnetic induction. This technique consists of a singlecoil acting as both an electromagnetic source and a receiver operatingtypically in the frequency range 1-10 MHz. When the coil is placed in afixed-geometric relationship to a conducting body, the alternatingelectric field in the coil generates electrical eddy current. A changein the bioimpedance induces changes in the eddy current, and as aresult, a change in the magnetic field of those eddy currents. The coilacts as a receiver to detect such changes. Experiments with thistechnique achieved sensitivity of 95%, and specificity of 69%,distinguishing between 1% metastasis tumor and 20% metastasis tumor.Distinguishing between tumor and normal tissue is even better.

Although the exact mechanism responsible for tissue impedance at certainfrequencies is not completely understood, the general mechanism^(14,15)is well explained by semi-empirical models that are supported byexperiments^(16,17,18).

Variations in electrical impedance of the human tissue are described inthe patent literature to provide indications of tumors, lesions andother abnormalities. For example, U.S. Pat. Nos. 4,291,708; 4,458,694;4.537,203; 4,617,939 and 4,539,640 exemplify prior art systems fortissue characterization by using multi-element probes which are pressedagainst the skin of the patient and measure impedance of the tissue togenerate a two-dimensional impedance map. Other prior techniques of thistype are described in WO 01/43630; U.S. Pat. Nos. 4,291,708 and5,143,079. However, the above devices use a set of electrodes that mustbe electrically contacted with the tissue or body, and therefore thecontact is usually a source of noise and also limits maneuverability ofthe probe over the organ.

Other prior patents, for example U.S. Pat. Nos. 5,807,257; 5,704,355 and6,061,589 use millimeter and microwave devices to measure bioimpedanceand to detect abnormal tissue. These methods direct a free propagatingradiation, or a guided radiation via waveguide, onto the organ. Theradiation is focused on a relatively small volume inside the organ, andthe reflected radiation is then measured. However, these methods lackaccuracy and spatial resolution since they are limited by thediffraction limit.

Another prior art technique is based on measurement of the resonancefrequency of a resonator as influenced by the tissue impedance. Thistechnique also uses radiation from an antenna, usually a small dipoleantenna attached to a coaxial line. Although non-contact, the deviceactually measures average values inside the organ, and its ability todetect small tumor is doubtful. Similar prior art is described in Xu,Y., et al. “Theoretical and Experimental Study of Measurement ofMicrowave Permitivity using Open Ended Elliptical Coaxial Probes”. IEEETrans AP-40(1), January 1992, pp 143-150.3. U.S. Pat. No. 6,109,270(2000 NASA) describes a measurement concept with a multi-modalityinstrument for tissue identification in real-time neuro-surgicalapplications.

Other known prior art includes an open-ended coaxial^(2,3,4) probehaving a center conducting wire surrounding by an insulator and enclosedin an external shield.

Other existing medical instruments provide general diagnoses for thedetection of interfaces between different types of tissues, such ascancerous tissue and healthy tissue, etc. However, such detections havebeen limited clinically to pre-operative scans, or demand large scanningmulti-million-dollar machines, like the MRI, CT, and Mammography.Furthermore, real-time attempts to use these detecting methods are verysensitive to movement of the body, and cannot really be used to positionthe cutting knife or the biopsy needle. Existing devices providediagnostic data of limited use since the tissue, sampled or removed,depends entirely upon the accuracy with which the localization providedby the preoperative CT, MRI, or US scan is translated to theintracranial biopsy site. Any movement of the organ or the localizationdevice results in an error in biopsy localization. Also, no informationabout the tissue being cut by the needle or knife is provided.

Detecting breast cancer tissues by measuring bioimpedance is thus wellestablished, and the ability of this technique for delineating cancerouscells inside the body has been proved. However, there is currently noreliable real-time bioimpedance measuring device of sufficiently highaccuracy for local tissue characterization and of a spatial resolutioncomparable to that provided by mammography.

SUMMARY OF THE INVENTION

The present invention relates to probes, systems, and methods for tissuecharacterization by its dielectric properties, wherein a physicalfeature of the probe is designed to define and delimit a tissue volume,at a tissue edge, where characterization takes place. Preferably, tissuecharacterization occurs substantially in real time.

The probe for tissue-edge characterization is configured for:

-   -   forming contact with a surface of a tissue;    -   applying electric signals, associated with a wavelength λ, to        the tissue;    -   generating localized electrical and magnetic fringe fields, in        the tissue, substantially in a near field, where x<<λ;    -   producing primary reflected electric signals from the tissue,        substantially only from near field; and    -   sensing the primary reflected electric signals, from the near        field of the tissue.

A novel feature of the probe is its including a physical feature,designed to define and delimit the near field of the tissue, at a tissueedge, where characterization takes place.

Thus, the probe for tissue-edge characterization comprises:

an inner conductor, having:

-   -   longitudinal axis L along an x-axis of an x;y;z coordinate        system; and    -   proximal and distal ends, with respect to a tissue, along the        x-axis, forming the two endpoints of the longitudinal axis L;    -   a first sharp edge 141, inherently associated with the proximal        endpoint; and    -   the at least one feature, substantially at the proximal end, for        forming at least one additional sharp edge, operative to enhance        the localized electrical fringe fields in the tissue, within a        well defined volume, at the near field, the tissue volume being        defined by physical parameters of the feature.

For example, the physical feature may be a wire spiral, having anoverall diameter D and a wire diameter d, or wire spacing d. The featureis designed to define and delimit the near field to a tissue volumetricdisk, of about a diameter D and a depth d′, which is of a same order ofmagnitude as d. Preferably, the relationship between the overalldiameter D and the feature size d is about:1/100D<d<½D,

where D may be between 2 mm and 10 cm. For example:

For D of about 10 cm, d may be between about 1 mm and about 5 cm.

For D of about 2 mm, d may be between about 20 μm and about 1 mm.

It will thus be appreciated that the depth dimension of the tissuevolumetric disk, d′, is defined by the feature dimensions to about anorder of magnitude.

The at least one feature, having the at least one additional sharp edgeis operative to enhance the localized electrical fringe fields, in thetissue volumetric disk, sufficiently, so as to make the sum of reflectedelectric signals from the tissue outside the tissue volumetric disk lessthan 1/10 of the primary reflected electric signals, thus making thereflected electric signals from the tissue outside the tissue volumetricdisk negligible, when compared with the primary reflected electricsignals from the tissue inside the tissue volumetric disk.

In this manner, tissue characterization is at a very localized,well-defined near field, namely, the tissue volumetric disk, withnegligible contributions from a far field.

The electrical fringe field is an electrical field that exists at anedge of a charged conductor. Electrical fringe field, as used herein, istime-dependent, as it is produced responsive to time-dependent electricsignals.

The electrical fringe field penetration is substantially to the depth d,which is substantially determined by the feature size of the conductor.The profile of the electrical fringe field in the tissue region to thedepth d depends on the dielectrical properties of the tissue, which inturn depend on the tissue type—different tissue types will producedifferent primary reflected electric signals, thus enabling the tissuecharacterization.

Moreover, the primary reflected electric signals carries with itinformation about the impedance and dielectric properties of theexamined tissue. In consequence, the time-domain-profile of the primaryreflected electric signals provides information useful for tissuecharacterization.

The electrical characteristics of the primary reflected electricalsignal are compared with those of the applied (incident) electricalsignal by sampling both electrical signals at a plurality of spaced timeintervals. Preferably, the sampling rate depends on the highestfrequency content of the signal, for example, a sampling rate of every20 nsec may be applied for a 10 Mhz signal, and a sampling rate of 0.02nsec may be applied for a 10 Ghz signal. The voltage magnitudes of thetwo electrical signals at the spaced time intervals are then compared.The reflection coefficient can be also obtained in the frequency domain,both amplitude and phase; and the frequency dependent complex impedanceof the tissue is then calculated using the theoretical relation betweenimpedance and reflection.

A first mode of characterization of the examined tissue may be effectedby comparing impedance and dielectric properties of the examined tissuewith previously stored impedance and dielectric properties of knownnormal and cancerous tissues. A second mode of characterization may beeffected by comparing the Cole-Cole parameters of the examined tissuewith those previously stored of known normal and cancerous tissues. Athird mode of characterization may be effected by comparing similaritiesbetween parametric representations of the signals reflected by theexamined tissue with those of previously stored of known normal andcancerous tissues.

In accordance with embodiments of the present invention, the generationof electrical fringe fields in the tissue, substantially to the depth d,as substantially determined by the feature size, with negligibleradiation penetrating into and reflected from the tissue beyond thedepth d, eliminates almost completely the propagating wave.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing of the present invention, suitable methods andmaterials are described below. In case of conflict, the patentspecification, including definitions, will control. In addition, thematerials, methods, and examples are illustrative only and not intendedto be limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings. With specific reference now tothe drawings in detail, it is stressed that the particulars shown are byway of example and for purposes of illustrative discussion of thepreferred embodiments of the present invention only, and are presentedin the cause of providing what is believed to be the most useful andreadily understood description of the principles and conceptual aspectsof the present invention. In this regard, no attempt is made to showstructural details of the present invention in more detail than isnecessary for a fundamental understanding of the present invention, thedescription taken with the drawings making apparent to those skilled inthe art how the several forms of the present invention may be embodiedin practice.

In the drawings:

FIG. 1 schematically illustrates an overall system with a probe fortissue-edge characterization, in accordance with an embodiment of thepresent invention;

FIG. 2 schematically illustrates a hand-held system with a probe fortissue-edge characterization, in accordance with another embodiment ofthe present invention;

FIGS. 3A-3E schematically illustrate various constructions of the probefor tissue-edge characterization, in accordance with embodiments of thepresent invention;

FIG. 4 schematically illustrates a probe constructed with a cavity, inaccordance with an embodiment of the present invention;

FIG. 5 schematically illustrates a probe with a coaxial cable operativeas a transmission line, in accordance with an embodiment of the presentinvention;

FIG. 6 schematically illustrates a probe constructed in accordance withembodiments of the present invention, connected to an external unit by aflexible coaxial line;

FIG. 7 schematically illustrates components of the external unit in thesystem of FIG. 6;

FIG. 8 illustrates a connector between the external unit components andthe coaxial line to the probe, in accordance with the present invention;

FIGS. 9A-9E schematically illustrate various inner constructions ofprobes for tissue-edge characterization, in accordance with embodimentsof the present invention;

FIGS. 10A-10C schematically illustrate an inner conductor and at leastone feature, substantially at the proximal end of the inner conductor,for forming at least one additional sharp edge, in accordance with anyone of the embodiments of FIGS. 9A-E;

FIGS. 11A-11C schematically illustrate an inner conductor and features,substantially at the proximal end of the inner conductor, for formingadditional sharp edges, in accordance with an embodiment of the presentinvention;

FIGS. 12A-12C schematically illustrate an inner conductor and features,substantially at the proximal end of the inner conductor, for formingadditional sharp edges, in accordance with still another embodiment ofthe present invention;

FIGS. 13A-13C schematically illustrate an inner conductor and features,substantially at the proximal end of the inner conductor, for formingadditional sharp edges, in accordance with yet another embodiment of thepresent invention;

FIGS. 14A-14C schematically illustrate an inner conductor and features,substantially at the proximal end of the inner conductor, for formingadditional sharp edges, in accordance with still another embodiment ofthe present invention;

FIGS. 15A-15C schematically illustrate an inner conductor and features,substantially at the proximal end of the inner conductor, for formingadditional sharp edges, in accordance with yet another embodiment of thepresent invention;

FIGS. 16A-16C schematically illustrate an inner conductor and features,substantially at the proximal end of the inner conductor, for formingadditional sharp edges, in accordance with still another embodiment ofthe present invention;

FIGS. 17A-17C schematically illustrate an inner conductor and at leastone feature, substantially at the proximal end of the inner conductor,for forming at least one additional sharp edge, in accordance with yetanother embodiment of the present invention;

FIGS. 18A-18C schematically illustrate an inner conductor and features,substantially at the proximal end of the inner conductor, for formingadditional sharp edges, in accordance with still another embodiment ofthe present invention;

FIGS. 19A-19C schematically illustrate an inner conductor and at leastone feature, substantially at the proximal end of the inner conductor,for forming at least one additional sharp edge, in accordance with yetanother embodiment of the present invention;

FIGS. 20A-20C schematically illustrate an inner conductor and features,substantially at the proximal end of the inner conductor, for formingadditional sharp edges, in accordance with still another embodiment ofthe present invention;

FIGS. 21A-21C schematically illustrate an inner conductor and features,substantially at the proximal end of the inner conductor, for formingadditional sharp edges, in accordance with yet another embodiment of thepresent invention;

FIGS. 22A-22C schematically illustrate an inner conductor and features,substantially at the proximal end of the inner conductor, for formingadditional sharp edges, in accordance with still another embodiment ofthe present invention;

FIGS. 23A-23C schematically illustrate an inner conductor and features,substantially at the proximal end of the inner conductor, for formingadditional sharp edges, in accordance with yet another embodiment of thepresent invention;

FIGS. 24A-24C schematically illustrate an inner conductor and features,substantially at the proximal end of the inner conductor, for formingadditional sharp edges, in accordance with still another embodiment ofthe present invention;

FIGS. 25A-25C schematically illustrate an inner conductor and features,substantially at the proximal end of the inner conductor, for formingadditional sharp edges, in accordance with yet another embodiment of thepresent invention;

FIGS. 25D-25E schematically illustrate the probe associated with FIGS.25A-25C, with inductive and resistive coupling, respectively, inaccordance with embodiments of the present invention;

FIGS. 26A-26C schematically illustrate an inner conductor and features,substantially at the proximal end of the inner conductor, for formingadditional sharp edges, in accordance with still another embodiment ofthe present invention;

FIGS. 27A-27C schematically illustrate an inner conductor and features,substantially at the proximal end of the inner conductor, for formingadditional sharp edges, in accordance with yet another embodiment of thepresent invention;

FIGS. 28A-28C schematically illustrate an inner conductor and features,substantially at the proximal end of the inner conductor, for formingadditional sharp edges, in accordance with still another embodiment ofthe present invention;

FIGS. 29A-29C schematically illustrate an inner conductor and features,substantially at the proximal end of the inner conductor, for formingadditional sharp edges, in accordance with yet another embodiment of thepresent invention;

FIGS. 30A-30C schematically illustrate an inner conductor and features,substantially at the proximal end of the inner conductor, for formingadditional sharp edges, in accordance with still another embodiment ofthe present invention;

FIGS. 31A-31C schematically illustrate an inner conductor and features,substantially at the proximal end of the inner conductor, for formingadditional sharp edges, in accordance with yet another embodiment of thepresent invention;

FIGS. 32A-32C schematically illustrate an inner conductor and features,substantially at the proximal end of the inner conductor, for formingadditional sharp edges, in accordance with still another embodiment ofthe present invention;

FIGS. 33A-33B schematically illustrate an inner construction of a probefor tissue-edge characterization, in accordance with an embodiment ofthe present invention;

FIGS. 33C-33D schematically illustrate an inner construction of a probefor tissue-edge characterization, in accordance with another embodimentof the present invention;

FIGS. 34A-34B schematically illustrate an inner construction of a probefor tissue-edge characterization, in accordance with still anotherembodiment of the present invention;

FIG. 35 schematically illustrates an inner construction of a probe fortissue-edge characterization, with two inner conductors, in accordancewith embodiments of the present invention;

FIG. 36 schematically illustrates a proximal view of a probe fortissue-edge characterization, in accordance with an embodiment, based onFIG. 35;

FIGS. 37A and 37B schematically illustrate a proximal view of anotherprobe for tissue-edge characterization, in accordance with embodiments,based on FIG. 35;

FIG. 38 schematically illustrates another inner construction of a probefor tissue-edge characterization, with two inner conductors, inaccordance with embodiments of the present invention;

FIG. 39 schematically illustrates a proximal view of a probe fortissue-edge characterization, in accordance with an embodiment, based onFIG. 38;

FIG. 40 schematically illustrates another inner construction of a probefor tissue-edge characterization, in accordance with embodiments of thepresent invention; and

FIG. 41 schematically illustrates a proximal view of a probe fortissue-edge characterization, in accordance with an embodiment, based onFIG. 41.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to probes, systems, and methods for tissuecharacterization by its dielectric properties, wherein a physicalfeature of the probe is designed to define and delimit a tissue volume,at the tissue edge, where characterization takes place. Preferably,tissue characterization occurs substantially in real time.

Before explaining at least one embodiment of the present invention indetail, it is to be understood that the present invention is not limitedin its application to the details of construction and the arrangement ofthe components set forth in the following description or illustrated inthe drawings. The invention is capable of other embodiments or of beingpracticed or carried out in various ways. Also, it is to be understoodthat the phraseology and terminology employed herein is for the purposeof description and should not be regarded as limiting.

Referring now to the drawings, FIG. 1 schematically illustrates anoverall system 110 with a probe 120 for tissue-edge characterization, inaccordance with an embodiment of the present invention.

The probe 120 for tissue-edge characterization is configured for:

-   -   forming contact with a surface 111 of a tissue 15;    -   applying electric signals, associated with a wavelength λ, to        the tissue 15;    -   generating localized electrical and magnetic fringe fields 112,        in the tissue 15, substantially in a near field 117, where x<<λ;    -   producing primary reflected electric signals from the tissue 15,        substantially only from near field 117; and    -   sensing the primary reflected electric signals, from the near        field 117 of the tissue 15.

A novel feature of the probe 120 is its including a physical feature142, designed to define and delimit the near field 117 of the tissue 15,where characterization takes place.

Thus, the probe 120 for tissue-edge characterization comprises:

an inner conductor 140, having:

-   -   a longitudinal axis L along an x-axis of an x;y;z coordinate        system; and    -   proximal and distal ends 121 and 129, with respect to a tissue        15, along the x-axis, forming the two endpoints of the        longitudinal axis L;    -   a first sharp edge 141, inherently associated with the proximal        endpoint 121; and    -   the at least one feature 142, substantially at the proximal end        121, for forming at least one additional sharp edge 142A,        operative to enhance the localized electrical fringe fields in        the tissue, within a well defined volume, at the near field, the        tissue volume being defined by the physical parameters of the        feature 142.

For example, the physical feature 142 may be a wire spiral, having anoverall diameter D and a wire diameter d, or wire spacing d. The feature142 is designed to define and delimit the near field 117 to a tissuevolumetric disk, of about a diameter D and a depth d′, which is of aboutthe same order of magnitude as d. Preferably, the relationship betweenthe overall diameter D and the feature size d is about, 1/100D<d<½D,where D may be between 2 mm and 10 cm. For example:

For D of about 10 cm, d may be between about 1 mm and about 5 cm.

For D of about 2 mm, d may be between about 20 μm and about 1 mm.

It will thus be appreciated that the depth dimension of the tissuevolumetric disk, d′, is defined by the feature dimensions to about anorder of magnitude.

The at least one feature 142, having the at least one additional sharpedge 142A is operative to enhance the localized electrical fringe fields112, in the tissue volumetric disk 115, sufficiently, so as to make thesum of reflected electric signals from the tissue 15 outside the tissuevolumetric disk 115 less than 1/10 of the primary reflected electricsignals, thus making the reflected electric signals from the tissue 15outside the tissue volumetric disk 115 negligible, when compared withthe primary reflected electric signals from the tissue 15 inside thetissue volumetric disk 115.

In this manner, tissue characterization is at a very localized,well-defined near zone 117, namely, the tissue volumetric disk 115, withnegligible contributions from a far zone 119.

As seen in FIG. 1, the probe 120 may be associated with an externalcontrol and instrumentation system 130 for signal generation andanalysis, which together form the overall system 110 for tissue-edgecharacterization.

Accordingly, the probe 120 may be associated with a transmission line156, directly connected to the probe 120, or coupled to the probe 120via a coupler 150, preferably, at the distal end 129. The transmissionline 156 leads to the external control and instrumentation system 130and is operative to transmit a signal to an inner conductor 140, forapplying electric signals to the tissue 15, and to transmit back aresponse signal, which corresponds to the primary reflected electricsignals.

The external control and instrumentation system 130 may include a signalgenerator 132, a signal analyzer 134, and a controller 136, with variousmemories. It will be appreciated that these may be integrated into asingle unit. A user interface may be provided, for example, in the formof a keyboard 135, for example, to input data such as patient details,date and time of a particular test, and other relevant data.

Additionally, the external control and instrumentation system 130 mayinclude read and write drives 131, for example, diskettes, CDs, and (or)DVDs, for input and output of predetermined operating parameters andsettings, and (or) in order to store test results. A USB port 133 forexample, for a disk-on-key, and other ports may be provided. A displayscreen 138 may display the response and may further be a touch screen,operative as a user interface, additional to or in place of the keyboard135.

The external control and instrumentation system 130 may further includeoutput means, for example, a printer or a facsimile.

Additionally or alternatively, the external control and instrumentationsystem 130 may be configured for Internet and (or) wireless internetconnection.

It will be appreciated that the systems described in FIGS. 6-8hereinbelow may similarly be employed.

Referring further to the drawings, FIG. 2 schematically illustrates ahand-held system 110 with the probe 120 for tissue-edgecharacterization, in accordance with another embodiment of the presentinvention.

Accordingly, in FIG. 2, the probe 120 is shown as part of a stand-alone,hand-held system 110 configured for internal signal generation andanalysis. As such, the control and instrumentation system 130 isintegrated with the probe 120, and includes the signal generator 132,the signal analyzer 134, the controller 136 and the various memories.Preferably, the stand-alone, hand-held system 110 further includes thedisplay screen 138, keys 135 as well as additional control keys 135A, aUSB port 133, internet connection, wireless internet connection, andother features, as known.

It will be appreciated that the features described in FIGS. 6-8hereinbelow may be employed with the stand-alone, hand-held system 110of FIG. 2.

Referring further to the drawings, FIGS. 3A-3E schematically illustratevarious constructions of the probe for tissue-edge characterization, inaccordance with embodiments of the present invention.

As seen in FIG. 3A, the probe 120 includes an inner conductor 140surrounded by a dielectric material 173A, an inner conductor 140defining the first sharp edge 141, which in accordance with the presentexample, is not configured for making contact with the tissue 15. The atleast one feature 142 is substantially at the proximal end 121, formingthe additional sharp edges 142A, associated with the sizes D and d,defined in the y-z plane, substantially parallel with the surface 111 ofthe tissue 15. The additional sharp edges 142A are configured for makingcontact with the tissue 15. The transmission line 156 is coupled to aninner conductor 140, via the coupler 150. In accordance with the presentembodiment, the feature 142 is exposed to air.

As seen in FIG. 3B, the feature 142 is embedded in a thin insulatinglayer of dielectric material 173B, of about 1-200 μm, for example, ofpolyimide (Kapton), Polytetrafluoroethylene-PTFE (tefon), PolyEtherlride(Ultem), or another dielectric material, as known.

As seen in FIG. 3C, a conductive outer sleeve 171A may be employed, forsurrounding an inner conductor 140 and the dielectric material 173Awithin. The conductive outer sleeve 171A serves as a return path forsignals generated at the proximal end 121 of the inner conductor 140.

In accordance with the present example, the feature 142 is inductivelycoupled to the conductive outer sleeve 171A.

As seen in FIG. 3D, the conductive outer sleeve 171A is employed, andthe feature 142 is resistively coupled to the conductive outer sleeve171A.

As seen in FIG. 3E, a thin layer of a dielectric material 173C isdeposited on the proximal end of the feature 142. Accordingly, the thinlayer of a dielectric material 173C makes contact with the tissuesurface 111, rather then the conductive elements of the feature 142.

Referring further to the drawings, FIG. 4 schematically illustrates aprobe constructed with a cavity, in accordance with an embodiment of thepresent invention.

As seen in FIG. 4, the conductive outer sleeve 171A extends proximally,beyond the feature 142, to form a cavity 44. The tissue edge ischaracterized within the cavity 44, as the cavity 44 is adapted forcontaining the tissue volumetric disk 115 therein. In some cases, theprobe outer conductor 171A may taper in slightly, at its proximal end121.

Referring further to the drawings, FIG. 5 schematically illustrates aprobe with a coaxial cable operative as a transmission line, inaccordance with an embodiment of the present invention. As seen in FIG.5, the transmission line 156 may be constructed as a coaxial cablehaving an inner conductor 179, an outer sleeve 171, and a dielectricmaterial 173 therebetween. The coaxial cable 156 is coupled to the probe120 via a coupler 152.

Referring further to the drawings, FIG. 6 schematically illustrates aprobe constructed in accordance with embodiments of the presentinvention, connected to an external unit 52 by a flexible transmissionline, for example, a coaxial line 51. Accordingly, a probe 120, such asthat illustrated in FIGS. 1-3E, coupled to one end of a flexible coaxialline 51; the opposite end of coaxial line 51 is connected to an externalunit 52 for supplying the electrical signals to the probe. The externalunit 52 is more particularly illustrated in FIG. 7, as including acomputer 53, a signals source 54 and a digitizing unit 55. Theelectrical signals may be in the form of, for example, a sinusoidalsignal, a square pulse, a triangular pulse, a chirped pulse, a modulatedpulse, a tailored pulse, or any other pulse known in the art.

The at least one feature 142, with the additional sharp edges 142Aproduce a modified coaxial mode, leading to a much stronger electricalfringing field in the tissue, in the volumetric disk 115. In this way,only the small portion of the biological tissue placed within the volumewhere the electric fringing field is present and is responsible for mostof the reflection of the applied electrical signals back into thetransmission line 51. The output impedance of the probe thus depends toa great extent on the impedance of the biological tissue within thevolume where the electric fringing field is present—the volumetric disk115. As a result, the reflected signal detected by the probe isdependent substantially on the impedance and dielectric properties ofthe tissue itself. This allows a well defined volume of sampled tissueimpedance to be calculated without affecting, or being affected by, thesurrounding tissues.

Referring further to the drawings, FIG. 7 schematically illustratescomponents of the external unit 52 in the system of FIG. 6.

As shown in FIG. 7, two sets of wires 56, 57 connect the computer 53 tothe signals source unit 54 and the digitizing unit 55. One set of wires56 are the timing control wires used to transmit trigger signals to thesignal source unit 54 and the digitizing unit 55; whereas the other setof wires 57 are the data transfer wires used to transfer data from andto the computer 53.

The computer 53 controls the signal durations and repetition rates, aswell as the signal voltage and form.

Referring further to the drawings, FIG. 8 illustrates a connectorbetween the external unit components and a coaxial line to the probe, inaccordance with embodiments of the present invention;

FIG. 8 illustrates an electrical signal coupler 58 connecting the signalsource unit 54, the digitizing unit 55, and the probe 120.

As shown in FIG. 8, these connections are made by an electrical signalcoupler 58 having one leg 58A connected to the coaxial line 51, a secondleg 58B connected to the signal source unit 54, and a third leg 58Cconnected to the digitizing unit 55.

Digitizing unit 55 samples, at a plurality of spaced time intervals,both the incident electrical signals, namely those applied to the probe120, and the reflected signals reflected by the examined tissue in thevolumetric disk 115.

The two time-domain arrays may also be transformed to the frequencydomain, for example, by a conventional FFT program, which is a standardtool for transforming time domain signals to the frequency domain.

The above-described procedure is repeated, e.g., 1,000-10,000 times, foreach measurement point. This result is 1,000-10,000 pairs of arrays, allof which are saved and transmitted to the analysis program of thecomputer 53.

Computer 53 compares the electrical characteristics of the reflectedelectrical signals with respect to those of the incident (applied)electrical signals to provide an indication of the impedance anddielectric properties of the examined tissue. This is done by samplingboth electrical signals at a plurality of spaced time intervals, andcomparing the voltage magnitudes of the two electrical signals at thespaced time intervals.

The foregoing comparison is made using one, or a combination of, type ofanalysis: (1) an impedance or dielectric function calculation, (2) aCole-Cole parameters calculation, and (3) Parametric representation ofthe reflection signal After the impedance and/or dielectric function ofthe examined tissue is calculated, it may also be analyzed according to,for example but not limited to, the following procedures for featureextraction:

The computer calculated the values of extreme point (Peaks) and specialfeatures, like the frequency at which the extreme points appear, theamplitude of the peaks, the average value of the function, the integralunder the real part of the dielectric function, the average value of thederivative, the maximum derivative, and the roots of the function. Allthese values are transferred as an array of parametric representation ofthe reflected signal to the decision-making program routine. For eachvalue the statistical variance is also calculated.

In the Cole-Cole Parameter analysis the Cole-Cole parameters τ and α ofthe sampled tissue are calculated from the dielectric function asfollows: $\begin{matrix}{{ɛ = {ɛ_{\infty} + \frac{\Delta\quad ɛ}{1 + \left( {j\quad\omega\quad\tau_{c}} \right)^{1 - \alpha}}}},{{\Delta\quad ɛ} = {ɛ_{s} - ɛ_{\infty}}}} & \left( {{Eq}.\quad 5} \right)\end{matrix}$

Where: e is the dielectric function of the sample; ε_(∞)is thedielectric function at infinite frequency=constant; ε₀ is the dielectricfunction under dc field=constant; and j is (−1)ˆ^(1/2)

For each value, the statistical variance is also calculated. Aftercalculation, the Cole-Cole parameters are transferred to thedecision-making program routine.

The decision making routine compares the results from any combination ofthe three types of analysis and the existing data from the memory bank.In the memory bank, data from known types of tissue is recorded,together with the tissue type name and the statistical variance. Thestatistical variance is used to define a volume surrounding the curve.

The matching condition is a standard statistical process which comparestwo sets of data. It uses all data for comparison. For example, if thedata matches data from a previously taken memory bank data, the programdisplays the type of tissue from which the databank sample was taken.

In case there is no match between stored (known) tissue data and theexamined tissue data, the most similar stored tissue data is chosen ascharacterizing the examined tissue. The most similar tissue is chosenaccording to the distance (in the phase space) between the two measuredpoints; alternatively, a user defined criterion may be applied. The usermay decide to find similarities, at certain measurement points, based onone, two, or more specific calculated parameters, ignoring all theothers. For example the user may decide to find similarities onlyaccording to the frequency at which a peak appears in the real-part ofthe dielectric function.

The decision making routine also compares the last-point measured to thecurrently measured point. The result of that process is to indicatemerely how similar the two points are to each other, without knowing thetype of tissue of the last point. The distance between two data pointsis considered as usually in statistics, and the decisions are displayedon the screen together with all data parameters.

Referring further to the drawings, FIGS. 9A-9E schematically illustratevarious inner constructions of probes for tissue-edge characterization,in accordance with embodiments of the present invention.

As seen in FIGS. 9A-9E, the feature 142 is a step reduction in diameterof the inner conductor 140, leading to addition sharp edges, due to thecorners formed by the step. The probe 120 itself may be constructed invarious ways, as follows, As seen in FIG. 9A, the inner conductor 140 ofthe probe 120 is of the diameter D, which generally defines the diameterof the volumetric disk 115 (FIG. 1).

An inner conductor 140 is surrounded by a dielectric material 173A,which in accordance with the present embodiment, is exposed to air.

The feature 142, being the step reduction in diameter, may be embeddedin a dielectric material 173B. Alternatively, the feature 142 may beexposed to air.

As seen in FIG. 9B, the probe 120 may further include the conductiveouter sleeve 171A.

As seen in FIG. 9C, the inner conductor 120 may be thinner than thediameter D, and the feature 142 may further include a conducting disk140A, which defines the diameter D, and from which the step change indiameter takes place.

In accordance with the present embodiment, the feature 142 isinductively coupled to the conductive outer sleeve 171A.

As seen in FIG. 9D, a layer of dielectric material 173C may be depositedon the feature 142, so that contact with the tissue surface 111 (FIG. 1)is made by the dielectric material 173C.

As seen in FIG. 9E, the conductive outer sleeve 171A may be extendedbeyond the feature 142, so as to form a cavity 44, where interactionwith the tissue volumetric disk 115 takes place. (See also FIG. 4.)

Referring further to the drawings, FIGS. 10A-10C illustrate side,proximal, and perspective views, respectively, of an inner conductor140, of FIG. 9A or 9B, in accordance with embodiments of the presentinvention. Accordingly, an inner conductor 140 has a circular crosssection, with the diameter D being substantially equal to 3 d.Additionally, an inner conductor 140 includes a proximal-end face 147,which is substantially a flat face, substantially parallel to the y;zplane, and the feature 142 issues from the proximal-end face 147. The atleast one feature 142 is a step reduction in the diameter D, by d,forming a step 142B, in the direction of +x. The step 142B creates theadditional sharp edge 142A.

As a result, the first sharp edge 141 and the additional sharp edge 142Aof the feature 142 form two concentric sharp edges, separatedsubstantially by d, when viewed from the proximal end 121, as seen inFIG. 10B.

The additional sharp edge 142A associated with the size d is operativeto enhance the localized electrical fringe fields 112, in the tissuevolumetric disk 115, of a general diameter D and of a depth of generallyd′ which is of about a same order of magnitude as d. The enhancement issufficiently so as to make the reflected electric signals from thetissue 15 outside the tissue volumetric disk 115 negligible, whencompared with the primary reflected electric signals.

It will be appreciated that the other embodiments described inconjunction with FIGS. 9C-9E may similarly apply.

Referring further to the drawings, FIGS. 11A-11C illustrate side,proximal, and perspective views, respectively, of an inner conductor140, in accordance with another embodiment of the present invention,wherein the at least one feature 142 is at least two step reductions inthe diameter D, by d, forming steps 142B, in the direction of +x, andcreating the additional sharp edges 142A.

Preferably, as seen in FIG. 11B, when viewed from the proximal end thesharp edges 142A appear as concentric circles, separated substantiallyby d. Furthermore, the first sharp edge 141 is also separated from itsadjacent sharp edge 142A substantially by d. The plurality of sharpedges 142A enhance the localized electrical fringe fields 112 in thetissue volumetric disk 115.

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E may similarly apply here as well.

Referring further to the drawings, FIGS. 12A-12C illustrate side,proximal, and perspective views, respectively, of an inner conductor140, in accordance with yet another embodiment of the present invention,wherein an inner conductor 140 includes a carved-out portion 149, in the−x direction, at the proximal end 121, and further wherein the at leastone feature 142 issues from the carved-out portion 149, so that the atleast one additional sharp edge 142A is substantially at the same xposition as the first sharp edge 141.

In accordance with the present embodiment, the at least one feature 142is step reductions in the diameter D, by d, forming steps 142B,alternating in directions between +x and −x.

When viewed from the proximal end (FIG. 12B), the sharp edges 142Aformed by the steps 142B appear as concentric circles, separatedsubstantially by d, enhancing the localized electrical fringe fields 112in the tissue volumetric disk 115. Preferably the first sharp edge 141is also separated from the nearest sharp edge 142A, by d.

It will be appreciated that many variations of step changes arepossible, for example, step increases in the diameter D, by d, in eitherthe +x or the −x direction, and various combinations of the +x and −xdirections.

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E may similarly apply here as well.

Referring further to the drawings, FIGS. 13A-13C illustrate side,proximal, and perspective views, respectively, of an inner conductor140, in accordance with still another embodiment of the presentinvention. As these Figures illustrate, an inner conductor 140 has apolygonal cross section. The diameter equivalent of the polygon isdefined here as the diameter of a circle of an area equal to the area ofthe polygon.

The at least one feature 142 is the polygon corners, which define theadditional sharp edges 142A. In the present example, D≈2d and thepolygon is a hexagon, so that when viewed from the proximal end (FIG.13B), the polygon corners are separated by distances d.

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E may similarly apply here as well. However,in place of a round disk 140A, a polygonal disk 140A may be employed.

Referring further to the drawings, FIGS. 14A-14C illustrate side,proximal, and perspective views, respectively, of an inner conductor140, in accordance with yet another embodiment of the present invention,illustrating the polygonal conductor 140, as is FIGS. 13A-13C, whereinthe at least one feature 142 further includes step changes in thediameter equivalent D, in a manner analogous to that of FIGS. 11A-11C,so as to create a series of sharp edges 142A of concentric polygons,separated by distances d, when viewed from the proximal end 121 (FIG.14B).

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E may similarly apply here as well. However,in place of a round disk 140A, a polygonal disk 140A may be employed.

Referring further to the drawings, FIGS. 15A-15C illustrate side,proximal, and perspective views, respectively, of an inner conductor140, in accordance with still another embodiment of the presentinvention, illustrating the polygonal conductor 140, as is FIGS.13A-13C, wherein the at least one feature 142 further includes stepchanges in the diameter equivalent D, alternating in directions between+x and −x, in a manner analogous to that of FIGS. 12A-12C, againcreating a series of sharp edges 142A of concentric polygons, whenviewed from the proximal end 121 (FIG. 15B).

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E may similarly apply here as well. However,in place of a round disk 140A, a polygonal disk 140A may be employed.

Referring further to the drawings, FIGS. 16A-16C illustrate side,proximal, and perspective views, respectively, of the inner conductor140, in accordance with yet another embodiment of the present invention,wherein D is substantially equal to 2d, and the inner conductor 140 iscarved out at the proximal end, as an inverse cone, to a depth nogreater than substantially d, in the −x direction, forming theinverse-cone, carved-out portion 149, wherein the at least one feature142 is the inverse cone apex, forming the at least one additional sharpedge 142A, and further wherein the first sharp edge 141 and the apex142A create two concentric sharp edges, separated substantially by d,when viewed from the proximal end 121 (FIG. 16B).

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E may similarly apply here as well.

Referring further to the drawings, FIGS. 17A-17C illustrate side,proximal, and perspective views, respectively, of an inner conductor140, in accordance with still another embodiment of the presentinvention. Accordingly, an inner conductor 140 further includes aproximal-end face 147, which is substantially flat, in the y;z plane,and D is substantially equal to 2d. The at least one feature 142 is aneedle 142, having a needle diameter δ (FIGS. 17A and 17B), which ispreferably no greater than substantially ½ d. Preferably, the needle 142issus from the center of the proximal-end face 147, its proximal endforming the at least one additional sharp edge 142A, so that the firstsharp edge 141 and the needle's sharp edge 142A create two concentricsharp edges, separated substantially by d, when viewed from the proximalend 121 (FIG. 17B).

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E may similarly apply here as well.

Referring further to the drawings, FIGS. 18A-18C illustrate side,proximal, and perspective views, respectively, of the inner conductor140, in accordance with still another embodiment of the presentinvention, wherein the inner conductor 140 is formed with carved grooves142, forming concentric sharp edge 142A, separated substantially by d,when viewed from the proximal end 121 (FIG. 18B).

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E may similarly apply here as well.

Referring further to the drawings, FIGS. 19A-19C schematicallyillustrates the inner conductor 140, with the feature 142 being a needleissuing from a carved out portion 149.

Accordingly, the inner conductor 140 has a conical proximal end, thecone being carved out in the −x direction, to a depth no greater thansubstantially D, forming an inverse-cone, carved-out portion 149,wherein the at least one feature 142 is a needle having a needlediameter δ, the needle issuing from the center of the inverse-cone,carved-out portion 149, its proximal end forming the at least oneadditional sharp edge 142A, wherein the first sharp edge 141 and theneedle's sharp edge 142A creates two concentric sharp edges, separatedsubstantially by d, when viewed from the proximal end 121 (FIG. 19B),and having substantially the same x position (FIG. 19A).

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E may similarly apply here as well.

Referring further to the drawings, FIGS. 20A-20C illustrate side,proximal, and perspective views, respectively, of an inner conductor140, in accordance with another embodiment of the present invention. Aninner conductor 140 includes the carved-out portion 149, in the proximalend 121, and the at least one feature 142 is a plurality of the needlesof the needle diameters δ, no greater than substantially ½ d, issuingfrom the carved-out portion 149, and separated substantially bydistances d, therebetween. The needles' proximal ends form a pluralityof sharp edges 142A, separated substantially by d therebetween, whenviewed from the proximal end 121 (FIG. 20B). Additionally, thecarved-out portion 149 forms an additional sharp edge 142A, preferablyseparated from the first sharp edge 141 substantially by the distance d,(FIG. 20B). Preferably, all the sharp edges have substantially the samex position (FIG. 20A).

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E may similarly apply here as well.

Referring further to the drawings, FIGS. 21A-21C illustrate side,proximal, and perspective views, respectively, of an inner conductor140, in accordance with yet another embodiment of the present invention,wherein the at least one feature 142 is a plurality of the needles ofthe needle diameters δ, no greater than substantially ½ d, issuing fromthe proximal-end face 147 of an inner conductor 140, and separatedsubstantially by distances d, therebetween, wherein the needles proximalends form a plurality of sharp edges 142A, separated substantially by dtherebetween, when viewed from the proximal end 121 (FIG. 21B).

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E may similarly apply here as well.

Referring further to the drawings, FIGS. 22A-22C illustrate side,proximal, and perspective views, respectively, of an inner conductor140, in accordance with still another embodiment of the presentinvention. Accordingly, the at least one feature 142 is a carving ofbars on the proximal-end face 147 of an inner conductor 140. The barsare of a thickness of substantially d and are separated substantially byd. The bars form a plurality of sharp edges 142A, separatedsubstantially by d therebetween, when viewed from the proximal end 121(FIG. 22B).

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E may similarly apply here as well.

Referring further to the drawings, FIGS. 23A-23C illustrate side,proximal, and perspective views, respectively, of an inner conductor140, in accordance with yet another th embodiment of the presentinvention. Accordingly, an inner conductor 140 has a square crosssection and the at least one feature 142 is a square checkerboardcarving, on the proximal-end face 147 of an inner conductor 140. Thecheckerboard carving is of squares of sides that are substantially d, sothat the squares form a plurality of sharp edges 142A, separatedsubstantially by d therebetween, when viewed from the proximal end 121(FIG. 23B).

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E may similarly apply here as well, yet wherethe disk 140A is employed it will have a rectangular cross section.

Referring further to the drawings, FIGS. 24A-24C illustrate side,proximal, and perspective views, respectively, of an inner conductor140, in accordance with still another embodiment of the presentinvention, similar to that of FIGS. 23A-23C; however, with an innerconductor 140 having a circular cross section.

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E may similarly apply here as well.

Referring further to the drawings, FIGS. 25A-25C illustrate side,proximal, and perspective views, respectively, of an inner conductor140, in accordance with yet another embodiment of the present invention.Accordingly, the at least one feature 142 is a square grid construction,formed of squares of sides that are substantially d, of the conductivewire of the wire diameter δ, the squares forming a plurality of sharpedges 142A, separated substantially by d therebetween, when viewed fromthe proximal end 121 (FIG. 25B).

Referring further to the drawings, FIGS. 25D and 25E schematicallyillustrate the probe 120 associated with FIGS. 25A-25C, wherein thefeature 142 is inductively coupled to the conductive outer sleeve 171A(FIG. 25D) or resistively coupled to the conductive outer sleeve 171A(FIG. 25E). Preferably, when the feature 142 is resistively coupled, asin FIG. 25E, the thin inner conductor shown in FIG. 25E is preferred tothe inner conductor of the diameter of substantially D, shown in FIGS.25A-25C.

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E may similarly apply here as well.

Referring further to the drawings, FIGS. 26A-26C illustrate side,proximal, and perspective views, respectively, of an inner conductor140, in accordance with still another embodiment of the presentinvention, wherein the at least one feature 142 is a wire constructionof slots, of the conductive wire of the wire diameter δ, and furtherwherein the slots are substantially of a width d, when viewed from theproximal end 121 (FIG. 26B).

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E and FIGS. 25D-25E may similarly apply hereas well.

Referring further to the drawings, FIGS. 27A-27C illustrate side,proximal, and perspective views, respectively, of an inner conductor140, in accordance with yet another embodiment of the present invention,wherein the at least one feature 142 is a wire construction, issuingfrom an inner conductor 140 and bent into shapes that define the size d,when viewed from the proximal end 121 (FIG. 27B), formed of theconductive wire of the wire diameter δ, no greater than substantially ½d.

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E and FIGS. 25D-25E may similarly apply hereas well.

Referring further to the drawings, FIGS. 28A-28C illustrate side,proximal, and perspective views, respectively, of an inner conductor140, in accordance with a still another embodiment of the presentinvention, wherein the at least one feature 142 is at least two wireconstructions, issuing from an inner conductor 140 and bent into shapesthat define the size d, when viewed from the proximal end 121 (FIG.28B), formed of the conductive wire of the wire diameter δ, no greaterthan substantially ½ d.

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E and FIGS. 25D-25E may similarly apply hereas well.

Referring further to the drawings, FIGS. 29A-29C illustrate side,proximal, and perspective views, respectively, of an inner conductor140, in accordance with yet another embodiment of the present invention,wherein the at least one feature 142 is a circular wire construction,issuing from an inner conductor 140 and bent into shapes that define thesize d, when viewed from the proximal end 121, formed of the conductivewire of the wire diameter δ, no greater than substantially ½ d.

It will be appreciated that two or more circular wire constructions maysimilarly be employed, for example, arranged as two or more concentricwire constructions, bent into shapes that define the size d, when viewedfrom the proximal end 121.

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E and FIGS. 25D-25E may similarly apply hereas well.

Referring further to the drawings, FIGS. 30A-30C illustrate side,proximal, and perspective views, respectively, of an inner conductor140, in accordance with still another embodiment of the presentinvention. Accordingly, D is substantially equal to 3d, and the at leastone feature 142 is a circular wire construction of the conductive wireof the wire diameter δ, wherein the first sharp edge 141 and the sharpedge 142A formed by the circular wire construction create two concentriccircular sharp edges, separated substantially by d, when viewed from theproximal end 121 (FIG. 30B).

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E and FIGS. 25D-25E may similarly apply hereas well.

Referring further to the drawings, FIGS. 31A-31C illustrate side,proximal, and perspective views, respectively, of an inner conductor140, in accordance with yet another embodiment of the present invention.The at least one feature 142 is a spiral wire constructions, which issubstantially flat, when viewed from the side (FIG. 35A). Preferably,the spiral is formed of the conductive wire of the wire diameter δ. Thesharp edges 142A formed by the spiral wire construction create a spiralof sharp edges 142A, separated substantially by d, when viewed from theproximal end 121 (FIG. 31B).

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E and FIGS. 25D-25E may similarly apply hereas well.

Referring further to the drawings, FIGS. 32A-32C illustrate side,proximal, and perspective views, respectively, of an inner conductor140, in accordance with still another embodiment of the presentinvention. The at least one feature 142 is a conical spiral wireconstructions, as viewed from the side (FIG. 32A). Preferably, thespiral is formed of the conductive wire of the wire diameter δ. Thesharp edges 142A formed by the spiral wire construction create a spiralof sharp edges 142A, separated substantially by d, when viewed from theproximal end 121 (FIG. 32B).

It will be appreciated that the other embodiments described inconjunction with FIGS. 9A-9E and FIGS. 25D-25E may similarly apply hereas well.

Referring further to the drawings, FIGS. 33A and 33B illustrate a probe120, wherein the feature 142 is helical spiral wire construction, whichis inductively coupled.

Referring further to the drawings, FIGS. 33C and 33D illustrate a probe120, wherein the feature 142 is flat spiral wire construction, which isinductively coupled.

Referring further to the drawings, FIGS. 34A and 34B illustrate a probe120, wherein the feature 142 is helical spiral wire construction, whichis resistively coupled.

Referring further to the drawings, FIG. 35 schematically illustrates aninner construction of a probe 120 for tissue-edge characterization, withfirst and second inner conductors 140B and 140C, in accordance withembodiments of the present invention.

Accordingly, the second inner conductor 140C serves as a return path forsignals generated at the proximal end 121 of the inner conductor 140. Itwill be appreciated that the features 142 associated with the first andsecond conductors may be inductively or resistively coupled.

Referring further to the drawings, FIG. 36 schematically illustrates aproximal view of a probe 120 for tissue-edge characterization, inaccordance with an embodiment, based on FIG. 35, and showing a feature142 associated with the two inner conductors 140B and 140C. In thepresent example, the feature 142 may be arranged as two combs that areinterlaced, each in communication with a different one of the innerconductors. The present example is thus of inductive coupling.

Referring further to the drawings, FIGS. 37A and 37B schematicallyillustrate proximal views of probes 120 for tissue-edgecharacterization, in accordance with embodiments, based on FIG. 35, andshowing other features 142, associated with the two inner conductors140B and 140C.

As seen in FIG. 37A, the feature 142 may be arranged as two concentricwire circles, each in communication with a different one of the innerconductors. FIG. 37A illustrates inductive coupling between the twoinner conductors, 140B and 140C.

As seen in FIG. 37B, the feature 142 is in physical communication withboth the first and the second inner conductors 140B and 140C. FIG. 37Billustrates resistive coupling between the two inner conductors.

Referring further to the drawings, FIGS. 38-39 schematically illustrateanother inner construction of a probe 120 for tissue-edgecharacterization, with two inner conductors, wherein the two innerconductors 140B and 140C and the conductive outer sleeve 171A areoperative in the signal path, in accordance with embodiments of thepresent invention.

As seen in FIG. 39, the feature 142 may be arranged as three concentricwire circles, two of which being in communication with the two innerconductors 140B and 140C, respectively, and a third being incommunication with the conductive outer sleeve 171A.

Referring further to the drawings, FIGS. 40 and 41 schematicallyillustrate another inner construction of a probe 120 for tissue-edgecharacterization, with a single inner conductor 140, wherein both theinner conductor 140 and the conductive outer sleeve-171A are operativein the signal path.

As seen in FIG. 41, the feature 142 may be arranged as two concentricwire circles, one of which being in communication with the innerconductor 140 and the other being in communication with the conductiveouter sleeve 171A.

It will be appreciated, with regard to the embodiments illustrated inFIGS. 35-41, that they may be operable also without the conductive outersleeve 171A.

In accordance with embodiments of the present invention, the probe 120may be employed as an extracorporeal probe or as an intracorporealprobe, for example, mounted on an endoscopic tool, as taught in commonlyowned U.S. patent application Ser. No. 10/567,581, whose disclosure isincorporated herein by reference.

Additionally, the probe 120 may be employed for detecting a cleanmargin, for example, as taught in commonly owned U.S. patent applicationSer. No. 10/558,831, whose disclosure is incorporated herein byreference.

Additionally, the probe 120 may be employed with effective contact, forexample, as taught in commonly owned applications U.S. patentapplication Ser. No. 11/350,102 and U.S. patent application Ser. No.11/196,732, whose disclosures are incorporated herein by reference.

In accordance with embodiments of the present invention, the probe 120may be employed during surgery.

In accordance with embodiments of the present invention, the feature 142of the probe 120 may be produced by applying a dielectric layer at theproximal end 121 of the probe, to serve as a substrate, and depositingthe feature 142 on the substrate, while providing conductivecommunication with the conductor 140, or with the first and secondconductors 140B and 140C. It will be appreciated that a film ofdielectric material may further be applied on the proximal side of thefeature 142.

It will be appreciated, with regard to embodiments that do not includethe conductive outer sleeve 171A, for example, as illustrated in FIGS.3A, 3B, and 9A, that in these cases, the fringe field generated in thetissue edge may extend beyond d′, which generally defines the depth ofthe tissue volumetric disk.

Although the present invention has been described in conjunction withspecific embodiments thereof, it is evident that many alternatives,modifications and variations will be apparent to those skilled in theart. Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims. All publications, patents, patent applicationsand sequences identified by their accession numbers mentioned in thisspecification are herein incorporated in their entirety by referenceinto the specification, to the same extent as if each individualpublication, patent, patent application or sequence identified by theiraccession number was specifically and individually indicated to beincorporated herein by reference. In addition, citation oridentification of any reference in this application shall not beconstrued as an admission that such reference is available as prior artto the present invention.

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1. A probe for tissue-edge characterization, comprising: a first innerconductor, which comprises: proximal and distal ends, with respect to atissue edge, along an x-axis; a first sharp edge, inherently associatedwith the proximal end; at least one feature, issuing from the firstinner conductor, substantially at the proximal end, for forming at leastone additional sharp edge, operative to enhance localized electricalfringe fields in the tissue, within a generally predefined tissuevolume, at the tissue edge, the tissue volume being generally defined byphysical parameters associated with the at least one feature; and adielectric material, which encloses the conductor, in the y-z planes. 2.The probe of claim 1, wherein the physical parameters of the at leastone feature include a general diameter D in the y-z plane and a featuresize d.
 3. The probe of claim 2, wherein the relationship between theoverall diameter D and the feature size d is about, 1/100 D<d<½ D, whereD may be between 2 mm and 10 cm.
 4. The probe of claim 2, wherein thetissue volume being generally defined by physical parameters of the atleast one feature is a volumetric disk of a diameter which is generallyD, and of a depth, which is generally d′ wherein d′ is generally of asame order of magnitude as d, the volumetric disk being at the tissueedge, where the probe makes contact with the tissue.
 5. The probe ofclaim 1, and further including a conductive outer sleeve, wherein theconductive outer sleeve serves as the return path for signals generatedat the proximal end of the first inner conductor.
 6. The probe of claim5, wherein the at least one feature and the conductive outer sleeve areresistively coupled.
 7. The probe of claim 5, wherein the at least onefeature and the conductive outer sleeve are inductively coupled.
 8. Theprobe of claim 5, wherein the at least one feature further includes atleast two features, one issuing from the first inner conductor andanother issuing from the conductive outer sleeve.
 9. The probe of claim5, wherein the conductive outer sleeve extends proximally beyond the atleast one feature, to form a cavity.
 10. The probe of claim 9, whereintissue-edge characterization occurs within the cavity.
 11. The probe ofclaim 1, and further including a second inner conductor, which serves asthe return path for signals generated at the proximal end of the firstinner conductor.
 12. The probe of claim 11, wherein the first and secondinner conductors are resistively coupled.
 13. The probe of claim 11,wherein the first and second inner conductors are inductively coupled.14. The probe of claim 11, wherein the at least one feature furtherincludes at least two features, one issuing from the first innerconductor and another issuing from the second inner conductor.
 15. Theprobe of claim 11, and further including a conductive outer sleeve. 16.The probe of claim 1, wherein the at least one feature includes at leasttwo features, issuing form the first inner conductor.
 17. The probe ofclaim 1, wherein the at least one feature is embedded in a dielectricmaterial.
 18. The probe of claim 17, wherein the dielectric materialextends proximally beyond the at least one feature, so that the tissueedge comes in contact only with the dielectric material.
 19. The probeof claim 1, wherein the at least one feature is configured for makingdirect contact with the tissue edge.
 20. The probe of claim 1,configured as a stand-alone, hand-held probe and further configured forsignal generation and signal analysis.
 21. The probe of claim 1, andfurther including a transmission line.
 22. The probe of claim 21,wherein the transmission line is formed as a coaxial cable.
 23. Theprobe of claim 21, connected to a transmission line at the distal end ofthe conductor, the transmission line being operative to transmit asignal to the conductor, for applying the electric signals to thetissue, and to transmit back a response signal, which corresponds to theprimary reflected electric signals.
 24. The probe of claim 1, formed asa coaxial probe.
 25. The probe of claim 1, wherein the at least onefeature is associated with a circular cross section and the diameter Dis the diameter of the circular cross section.
 26. The probe of claim 1,wherein the at least one feature is associated with a cross section of apolygonal, and the diameter D is the diameter of a circle of an areaequal to the area of the polygon.
 27. The probe of claim 1, wherein D issubstantially equal to 3d and the at least one feature is a step changein the diameter equivalent D, the change in the diameter equivalent Dbeing substantially by the size d, and the step being in a directionselected from the group consisting of +x and −x, wherein the first sharpedge and the step change form two concentric sharp edges, separatedsubstantially by d, when viewed from the proximal end.
 28. The probe ofclaim 1, wherein the at least one feature is at least two step changesin the diameter equivalent D, the changes in the diameter equivalent Dbeing substantially of the size d in the y;z plane, and the steps beingin directions selected from the group consisting of +x and −x, whereinthe at least two step changes form concentric sharp edges, separatedsubstantially by d, when viewed from the proximal end.
 29. The probe ofclaim 1, wherein the conductor has a polygon cross section, and the atleast one feature are the polygon corners, forming sharp edges,separated substantially by d, when viewed from the proximal end.
 30. Theprobe of claim 1, wherein: the conductor further includes a carved-outportion at the proximal end, the carved-out portion being shaped as aninverse cone; D is substantially equal to 2d; the at least one featureis an apex of the inverse cone, forming the at least one additionalsharp edge; and the first sharp edge and the inverse-cone apex createtwo concentric sharp edges, separated substantially by d, when viewedfrom the proximal end.
 31. The probe of claim 1, wherein: the conductorfurther includes a cone-shaped proximal end; D is substantially equal to2d; the at least one feature is an apex of the cone, forming the atleast one additional sharp edge; and the first sharp edge and the coneapex create two concentric sharp edges, separated substantially by d,when viewed from the proximal end.
 32. The probe of claim 1, wherein:the conductor further includes a proximal-end face, which issubstantially flat, in the y;z plane; D is substantially equal to 2d;the at least one feature is a needle having a needle diameter δ, whichis no greater than substantially ½ d, needle the needle issuing from thecenter of the proximal-end face, the needle's proximal end forming theat least one additional sharp edge; and the first sharp edge and theneedle's sharp edge create two concentric sharp edges, separatedsubstantially by d, when viewed from the proximal end.
 33. The probe ofclaim 1, wherein: the conductor further includes a carved-out portion atthe proximal end, shaped as an inverse cone; D is substantially equal to2d; the at least one feature is a needle having a needle diameter δ,which is no greater than substantially ½ d, and having a needle lengthin the +x direction, no greater than substantially d, the needle issuingfrom the center of the inverse-cone, carved-out portion, the needle'sproximal end forming the at least one additional sharp edge; and thefirst sharp edge and the needle's sharp edge create two concentric sharpedges, separated substantially by d, when viewed from the proximal endand having substantially the same x position.
 34. The probe of claim 1,wherein the at least one feature is a plurality of needles of needlediameters δ, no greater than substantially ½ d, issuing from aproximal-end face of the conductor, and separated substantially bydistances d, therebetween, wherein the needles proximal ends form aplurality of sharp edges, separated substantially by d therebetween,when viewed from the proximal end.
 35. The probe of claim 1, wherein:the conductor further includes a carved-out portion at the proximal end;the at least one feature is a plurality of needles of needle diametersδ, no greater than substantially ½ d, issuing from the carved outportion, and separated substantially by distances d, therebetween,wherein the needles proximal ends form a plurality of sharp edges,separated substantially by d therebetween, when viewed from the proximalend, and having substantially the same x position as the first sharpedge.
 36. The probe of claim 1, wherein the at least one feature is acarving of concentric circles in a proximal-end face, the concentriccircles being separated substantially by d, when viewed from theproximal end.
 37. The probe of claim 1, wherein the at least one featureis a carving of concentric polygons in a proximal-end face, theconcentric polygons being separated substantially by d, when viewed fromthe proximal end.
 38. The probe of claim 1, wherein the at least onefeature is a carving of bars in a proximal-end face, wherein the barsare of a thickness of substantially d, and are separated substantiallyby d, wherein the bars form a plurality of sharp edges, separatedsubstantially by d therebetween, when viewed from the proximal end. 39.The probe of claim 1, wherein the at least one feature is a squarecheckerboard carving, in a proximal-end face, the checkerboard carvingbeing formed of squares of sides that are substantially d, wherein thesquares form a plurality of sharp edges, separated substantially by dtherebetween, when viewed from the proximal end.
 40. The probe of claim1, wherein the at least one feature is at least one wire construction,of a conductive wire of a wire diameter δ, which is no greater thansubstantially ½ d, the wire construction issuing substantially at theproximal-end.
 41. The probe of claim 40, wherein the at least one wireconstruction is a tire-shape spiral construction, wherein the windingsof the tire-shape spiral construction are substantially of the size d,forming sharp edges, separated substantially by d, when viewed from theproximal end.
 42. The probe of claim 40, wherein the at least one wireconstruction is a toroid spiral construction, which appears as a disk ina side view and as a toroid spiral in a proximal view, wherein thewindings of the spiral are substantially of the size d, forming aplurality of sharp edges, separated substantially by d, when viewed fromthe proximal end.
 43. The probe of claim 40, wherein the at least onewire construction is a square grid construction, formed of squares ofsides that are substantially d, the squares forming a plurality of sharpedges, separated substantially by d therebetween, when viewed from theproximal end.
 44. The probe of claim 40, wherein the at least one wireconstruction is a wire construction of slots, wherein slots aresubstantially of a width d, when viewed from the proximal end.
 45. Theprobe of claim 40, wherein the at least one wire construction is twointerlaced comb-like constructions, wherein the interlaced teeth of thetwo comb-like constructions are separated substantially by d, whenviewed from the proximal end.
 46. The probe of claim 40, wherein the atleast one wire construction is a wire construction bent into shapes thatdefine the size d, when viewed from the proximal end.
 47. The probe ofclaim 40, wherein the at least one wire construction is at least twowire construction bent into shapes that define the size d, when viewedfrom the proximal end.
 48. The probe of claim 40, wherein the at leastone wire construction is a circular wire construction, wherein the firstsharp edge and the sharp edge formed by the circular wire constructionform two concentric circular sharp edges, separated substantially by d,when viewed from the proximal end.
 49. The probe of claim 40, whereinthe at least one wire construction is at least two circular wireconstructions, wherein the sharp edges formed by the circular wireconstructions create concentric circular sharp edges, separatedsubstantially by d, when viewed from the proximal end.
 50. The probe ofclaim 40, wherein the at least one wire construction is a spiral wireconstruction, wherein the spiral wire construction forms sharp edges,separated substantially by d, when viewed from the proximal end.
 51. Theprobe of claim 40, wherein the spiral-wire construction is flat, in aside view.
 52. The probe of claim 40, wherein the spiral-wireconstruction is conical, in a side view.
 53. The probe of claim 40,wherein the at least one wire construction is two interlaced spiral wireconstructions, wherein the spiral wire constructions form sharp edges,separated substantially by d, when viewed from the proximal end.
 54. Theprobe of claim 53, wherein the spiral-wire constructions are flat, in aside view.
 55. The probe of claim 53, wherein the spiral-wireconstructions are conical, in a side view.
 56. The probe of claim 1,wherein the at least one feature is at least one deposited conductor, ofa thickness δ in the y;z plane, δ being no greater than substantially ½d, the deposited conductor being deposited on a substrate, which isarranged at the proximal-end.
 57. A system for tissue-edgecharacterization, comprising: a probe for tissue-edge characterization,which comprises: a first inner conductor, which comprises: proximal anddistal ends, with respect to a tissue edge, along an x-axis; a firstsharp edge, inherently associated with the proximal end; at least onefeature, issuing from the first inner conductor, substantially at theproximal end, for forming at least one additional sharp edge, operativeto enhance localized electrical fringe fields in the tissue, within a agenerally predefined tissue volume, at the tissue edge, the tissuevolume being generally defined by physical parameters associated withthe at least one feature; and a dielectric material, which encloses theconductor, in the y-z planes; an external control and instrumentationsystem, for signal generation and signal analysis; and a transmissionline, for connecting between the probe and the external control andinstrumentation system.
 58. The system of claim 57, wherein thetransmission line is a coaxial cable.
 59. The system of claim 57,wherein the external control and instrumentation system comprises: asignal generator, in communication with the probe, via the transmissionline, for generating the electric signals; a detector, in communicationwith the probe, via the transmission line, for detecting the reflectedelectric signals; and a data processor for comparing electricalcharacteristics of the reflected electric signals with respect to theapplied electric signals to produce an indication of the dielectricproperties of tissue for examination.
 60. The system of claim 59,wherein the electric signals are selected from the group consisting of:a sinusoidal signal, a square pulse, a triangular pulse, a chirpedpulse, a modulated pulse, a tailored pulse, and a combination thereof.61. The system of claim 59, wherein the signal generator is configuredfor generating and applying electric signals of duration of the order ofnanoseconds.
 62. The system of claim 59, wherein the signal generator isconfigured for generating and applying electric signals of duration ofthe order of picoseconds.
 63. The system of claim 59, wherein: thesignal generator is configured for generating and applying a series ofthe electric signals at a pulse repetition rate of a few Herz to a fewgiga-Herz.
 64. The system of claim 59, wherein: the detector isconfigured for detecting the primary reflected electric signals; and thedata processor is configured for comparing the primary reflectedelectric signals with the applied electric signals, to provide anindication of the impedance of the generally predefined tissue volume,at the tissue edge.
 65. The system of claim 59, wherein: the detector isconfigured for detecting the primary reflected electric signals; and thedata processor is configured for comparing the primary reflectedelectric signals with the applied electric signals, to provide anindication of the dielectric properties of the generally predefinedtissue volume, at the tissue edge.
 66. The system of claim 59, whereinthe detector is a digitizing unit.
 67. The system of claim 57,configured for sensing in real time.
 68. A method for tissue-edgecharacterization, comprising: providing a probe for tissue-edgecharacterization, comprising: a first inner conductor, which comprises:proximal and distal ends, with respect to a tissue edge, along anx-axis; a first sharp edge, inherently associated with the proximal end;at least one feature, issuing from the first inner conductor,substantially at the proximal end, for forming at least one additionalsharp edge, operative to enhance localized electrical fringe fields inthe tissue, within a a generally predefined tissue volume, at the tissueedge, the tissue volume being generally defined by physical parametersassociated with the at least one feature; and a dielectric material,which encloses the conductor, in the y-z planes. bringing the probe toform contact with the tissue edge; applying electric signals, associatedwith a wavelength λ, to the tissue; generating the enhanced localizedelectrical fringe fields in the tissue, within the generally predefinedtissue volume, at the tissue edge; producing primary reflected electricsignals from the tissue, substantially only from the predefined tissuevolume, at the tissue edge; and sensing the primary reflected electricsignals, from the predefined tissue volume, at the tissue edge.